/*******************************************************************************
 * Copyright 2014 The MITRE Corporation
 *   and the MIT Kerberos and Internet Trust Consortium
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package org.dromara.maxkey.crypto.jwt.signer.service.impl;

import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import org.dromara.maxkey.crypto.jwt.signer.service.JwtSigningAndValidationService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;

import com.google.common.base.Strings;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableMap;
import com.google.common.util.concurrent.UncheckedExecutionException;
import com.nimbusds.jose.jwk.JWK;

/**
 * Creates and caches symmetrical validators for clients based on client secrets.
 * 
 * @author jricher
 *
 */
@Service
public class SymmetricCacheService {

    private static Logger logger = LoggerFactory.getLogger(SymmetricCacheService.class);

    private LoadingCache<String, JwtSigningAndValidationService> validators;


    public SymmetricCacheService() {
        validators = CacheBuilder.newBuilder()
                .expireAfterAccess(24, TimeUnit.HOURS)
                .maximumSize(100)
                .build(new SymmetricValidatorBuilder());
    }


    /**
     * Create a symmetric signing and validation service for the given client
     * 
     * @param client
     * @return
     */
    public JwtSigningAndValidationService getSymmetricValidtor(String clientSecret) {

        if (clientSecret == null) {
            logger.error("Couldn't create symmetric validator for null client");
            return null;
        }

        if (Strings.isNullOrEmpty(clientSecret)) {
            logger.error("Couldn't create symmetric validator for client  without a client secret");
            return null;
        }

        try {
            return validators.get(clientSecret);
        } catch (UncheckedExecutionException ue) {
            logger.error("Problem loading client validator", ue);
            return null;
        } catch (ExecutionException e) {
            logger.error("Problem loading client validator", e);
            return null;
        }

    }

    public class SymmetricValidatorBuilder extends CacheLoader<String, JwtSigningAndValidationService> {
        @Override
        public JwtSigningAndValidationService load(String key) throws Exception {
            try {

                String id = "SYMMETRIC-KEY";

                JWK jwk =null;
                //JWK jwk = new OctetSequenceKey(Base64URL.encode(key), KeyUse.SIGNATURE, null, null, id, null, null, null);
                Map<String, JWK> keys = ImmutableMap.of(id, jwk);
                JwtSigningAndValidationService service = new DefaultJwtSigningAndValidationService(keys);

                return service;

            } catch (NoSuchAlgorithmException e) {
                logger.error("Couldn't create symmetric validator for client", e);
            } catch (InvalidKeySpecException e) {
                logger.error("Couldn't create symmetric validator for client", e);
            }

            throw new IllegalArgumentException("Couldn't create symmetric validator for client");
        }

    }

}
